Fibrous materials such as straw from flax, sisal, hemp, jute and coir, banana, among others, are used or combined with various polymers in the formation of biocomposite, or bio-fiber composite materials. Biocomposite materials utilizing these fibrous materials or fibers mixed with selected polymers provide enhanced desirable properties, such as increased strength, to the biocomposite material compared with polymer-only materials.
However, when the biocomposite material is formed, it is often desired to color the biocomposite material due to the particular use or product into which the biocomposite material is formed. Colorants are used in these biocomposite materials in order to increase the brand identity and aesthetic appeal of the products made from these materials. To accomplish this various colorants are utilized. These colorants are intermixed with the biocomposite material and provide the biocomposite material with the desired color for the end use of the biocomposite material. In one example of the use of colorants with biocomposite materials, these materials are colored by pre-coloring the fibrous material with liquid colorant before combining the fibrous material with the polymer base to form the biocomposite material. For example, the fibrous material and colorant are placed within a suitable container and boiled in order to bond the colorant to the fibrous material.
However, a significant problem with coloring bio-fiber composite materials is that the fibrous material, e.g., the cellulose material, interacts with the colorant differently than the polymer component of the biocomposite material resulting in an inconsistent finish/coloration over the entirety of the product formed with the biocomposite material and colorant.
Further, traditional methods for introducing the colorant into the biocomposite material, such as boiling, can damage the fibrous material, which can significantly degrade the strength of the fibrous material. This can result in the fibrous material acting within the biocomposite material as a filler material instead of a strength-enhancer.
As a result, it is desirable to develop an improved method for adding or introducing a colorant into a biocomposite formed with a fibrous material and polymer base in that provide a uniform color finish over the entire biocomposite material product, while not detrimentally affecting the strength/reinforcement properties of the fibrous material in the biocomposite.